1. Field
The present invention relates to a system, method and apparatus for pressurizing fluid to power a load. More particularly, the invention relates to series-parallel arrangements of pressurization units, including multi-stage pressurization units, connected to power loads such as reservoirs, generators, extractors (such as desalinators and carbon dioxide sequestrators), and injectors (such as hypoxia-reducing air injectors) for example, either directly or via a manifold to power more than one load. More particularly, the invention relates to aquatic deployment of pressurization units, wherein each pressurization unit includes a submersible standardized cylinder and a tailored float selected for efficient operation with reference to the characteristics of the standardized cylinder, the wave characteristics of the aquatic environment, and the desired fluid pressure operating range of the pressurization unit.
2. Description of Related Art
A great variety of approaches have been proposed to generate energy from waves. One common approach is to deploy a float that rides up and down with wave motion relative to a fixed or anchored member that remains relatively stationary. An air compression cylinder is introduced between the float and the stationary member, which in cooperation with intake and output conduits and associated check valves receives, compresses and supplies air that is accumulated as the float rises and falls with the wave motion and urges the cylinder to extend and retract. Variations to such pressurization units have been made to pressurize liquids or to pump water to fill an elevated water reservoir on shore. The potential energy stored in the pressurized fluid, e.g. air or water, is then used to drive a conventional machine such as a turbine/generator set to supply electrical energy.
Conventional single unit devices and multiple arrays of units conventionally connected in parallel suffer from the disadvantage that a relatively high minimum amplitude of wave must be encountered before the pressure in the cylinder reaches a level at which useable pressurized fluid is generated. As a result, waves having an amplitude below such a minimum threshold do not generate any energy. The minimum amplitude is determined by the design of the pressurizing cylinder, and this disadvantage is present in both single unit devices and multiple unit arrays of the conventional methods and devices.
The applicant's U.S. Pat. No. 5,179,837, U.S. Pat. No. 5,394,695 and U.S. Pat. No. 7,690,900 disclose methods and systems for generating energy from the motion of waves by a plurality of series-connected floating pressurization units, wherein each unit incrementally increases the pressure in a compression fluid flowing therethrough using energy in water waves. The system provides for a new ambient pressure starting point at each stage in the series, such that each successive downstream stage has a higher initial pressure than the previous stage(s). Energy is transferred from the waves to the fluid by relative movement between a first floating portion and second submerged portion of the unit. The second portion has a piston that extends upwardly into a compression chamber of the second portion. Vertical oscillation of the first portion as it reacts to the wave causes the piston and chamber to vertically move relative to each other, thereby pressurizing the fluid in the chamber and driving the fluid through an outlet valve to an intermediate reservoir and then to the next adjacent pressurization unit. When the cylinder bottom stops moving away from the piston, fluid pressurization stops and new fluid flows into the cylinder. The outlet valve is biased to open at a selected outlet pressure; when the pressure in the chamber decreases below the outlet pressure, fluid transmission from the chamber stops, but transmission from the intermediate reservoir to the next pressurization unit continues. Therefore, fluid tends to be conveyed through the device in pressurized pulses, wherein the oscillation of the pulses depends on the oscillation of the waves.
Although extremely useful, a series system still presents certain challenges for some applications. For example, the pressurized fluid that expands to power a load, whether exhausted or recycled back to the first pressurizing unit in the series, depressurizes to a low pressure, for example atmospheric pressure. Continued operation requires fully pressurizing fluid from atmospheric pressure, always starting from the first pressurization unit at the beginning of the series.
Furthermore, that full expansion is a thermal sink that, if large enough, can freeze proximate equipment. It would be desirable to be able to harness an expansion of a high pressure range of an nth stage in a closed loop system, since high pressure operation can permit lower fluid volumes and hence smaller system components.
It would also be desirable to build such a system with a network of standardized pressurization units (and where possible, through topology or otherwise, using at least some identical pressurization units) to take advantage of manufacturing and maintenance efficiencies from economies of scale. It would also be desirable to build such a system so as to simplify deployment, for example by deploying fewer pressurization units and deploying fewer conduits between them. It would also be desirable to configure the pressurization units and the conduits to better resist exterior and interior pressures.
Finally, it would be desirable to configure such a system to provide multiple functions simultaneously or otherwise, for example a combination of generating power, desalinating sea water, sequestering carbon dioxide and counteracting hypoxia.